Atom Probe Mass Spectrometry of Uranium Isotopic Reference Materials

Area of Science:

• Materials Science
• Nuclear Science
• Geochemistry

Background:

• Atom probe tomography (APT) is increasingly used for high-resolution isotopic analysis.
• Concerns exist regarding the reliability of APT isotopic and elemental measurements.
• Standardized analysis guidelines are needed for critical applications.

Purpose of the Study:

• To validate the accuracy and repeatability of uranium isotopic analysis using APT.
• To establish reliable methodologies for sub-micrometer isotopic measurements.
• To address the open question of APT analysis reliability.

Main Methods:

• Utilized U3O8 isotopic reference materials for empirical calibration.
• Implemented a machine learning-based adaptive peak fitting algorithm.
• Developed and applied proposed analysis guidelines for APT data interpretation.

Main Results:

• Achieved accurate and repeatable uranium isotopic measurements for 235U and 238U.
• Isotopic abundance values were consistently within ±1.5% of certified reference values.
• Demonstrated accuracy approaching the theoretical limit imposed by Poisson counting statistics.

Conclusions:

• The proposed APT analysis guidelines, calibration, and machine learning algorithm ensure reliable uranium isotopic quantification.
• APT is a viable technique for accurate sub-micrometer isotopic analysis in fields like geochemistry and nuclear safety.
• The findings contribute to establishing confidence in APT-based isotopic and elemental analysis.